A unique visitor potentially can be reported as up to four different people, when accessing AMP pages.

When a visitor navigates from an AMP page to a regular page in a site, that causes a new session to be generated, even though technically, it was the same session.

Bounce rate will appear higher than normal when AMP pages are involved, because since new sessions are generated as described above, it appears as if visitors are leaving quickly when they are not.

Pageviews per session will appear lower, when an AMP person moves from an AMP page to a regular page in a single session.

Visitors who come to AMP page from search and then goes to another page will appear as if they are new visitors coming from referral traffic, rather than search.

Oliveira documents a solution to this, but it’s not for everyone nor perfect. Hopefully, Google will accelerated efforts on its end to come up with a solution, but that doesn’t look to be coming quickly, based on Ubi’s tweets.